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At least 1,135 records · Page 63Linked to original sources

Trondhjemitic, 1.35-1.31 Ga gneisses of the Mount Holly Complex of Vermont: evidence for an Elzevirian event in the Grenville Basement of the United States Appalachians

A newly recognized suite of trondhjemite–tonalite and dacitic gneiss forms a 10 km wide belt of rocks within the Mount Holly Complex in the central part of the Green Mountain massif of Vermont. Field relationships and chemistry indicate that these gneisses are calc-alkaline, volcanic, and hypabyssal plutonic rocks older than the Middle Proterozoic regional deformation that affected the Mount Holly Complex. U–Pb zircon dates indicate ages as great as 1.35 Ga for crystallization of the volcanic protoliths and for intrusion of crosscutting trondhjemite. Tonalitic plutonism continued until 1.31 Ga.Map-scale contacts between the trondhjemitic–tonalitic–dacitic gneisses and the paragneiss sequence of the Mount Holly Complex are sharp, suggesting that the volcanic rocks of the trondhjemite–tonalite suite underlie the paragneiss units and do not intrude them. These relationships suggest that the trondhjemite–tonalite suite is either considerably older than, and unconformable beneath, the paragneiss cover rocks or represents a volcanic edifice slightly older than the deposition of the sedimentary precursor to the paragneiss units. The paragneiss and tonalite–trondhjemite gneisses are both intruded by younger granitoids that were intruded at about 1.25 Ga during strong dynamothermal metamorphism.The trondhjemitic gneisses of the Mount Holly Complex of Vermont have high Al 2 O 3 and low Yb contents and light rare-earth element enrichment patterns that are more characteristic of continental than oceanic volcanic arcs. The Mount Holly intrusives and volcanics may have formed during 1.35–1.31 Ga ensialic volcanic-arc activity, contemporaneous with ensimatic arc activity during the early part of the Elzevirian phase of the Grenville orogeny. In Vermont, later deformation and granite intrusion at about 1.25 Ga coincide with the major pulse of the Elzevirian orogeny and associated trondhjemitic plutonism in the Central Metasedimentary Belt of eastern Canada.

Vermont↗

Evidence for cumulative temperature as an initiating and terminating factor in downstream migratory behavior of Atlantic salmon (Salmo salar) smolts

Temperature control of Atlantic salmon (Salmo salar) smolt migration was tested using a novel technique allowing nearly continuous monitoring of behavior with complete control over environmental conditions. Parr and presmolts were implanted with passive integrated transponder tags, placed in simulated streams, and monitored for upstream and downstream movements. Beginning 18 April, temperature was increased 1??C every third day (advanced), fourth day (ambient), and tenth day (delayed). Smolt downstream movements were initially low, peaked in mid-May, and subsequently declined under all conditions. Parr downstream movements were significantly lower than those of smolts in all treatments (0.8 ?? 0.5 movement??day-1 versus 26.5 ?? 4.5 movements??day-1, mean ?? SE) and showed no increase. At delayed temperatures, smolts sustained downstream movements through July; those under ambient and advanced conditions ceased activity by mid-June. Initiation and termination of downstream movements occurred at significantly different temperatures but at the same number of degree-days in all treatments. Physiological changes associated with smolting (gill Na+,K +-ATPase activity and plasma thyroxine) were coincident with behavioral changes. This is the first evidence of a behavioral component to the smolt window. We found that temperature experience over time is more relevant to initiation and termination of downstream movement than a temperature threshold. ?? 2005 NRC Canada.

Canadian Journal of Fisheries and Aquatic Sciences↗

The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

Journal of Geophysical Research E: Planets↗

A science-based, watershed strategy to support effective remediation of abandoned mine lands

A U.S. Geological Survey Abandoned Mine Lands Initiative will develop a strategy for gathering and communicating the scientific information needed to formulate effective and cost-efficient remediation of abandoned mine lands. A watershed approach will identify, characterize, and remediate contaminated sites that have the most profound effect on water and ecosystem quality within a watershed. The Initiative will be conducted during 1997 through 2001 in two pilot watersheds, the Upper Animas River watershed in Colorado and the Boulder River watershed in Montana. Initiative efforts are being coordinated with the U.S. Forest Service, Bureau of Land Management, National Park Service, and other stakeholders which are using the resulting scientific information to design and implement remediation activities. The Initiative has the following eight objective-oriented components: estimate background (pre-mining) conditions; define baseline (current) conditions; identify target sites (major contaminant sources); characterize target sites and processes affecting contaminant dispersal; characterize ecosystem health and controlling processes at target sites; develop remediation goals and monitoring network; provide an integrated, quality-assured and accessible data network; and document lessons learned for future applications of the watershed approach.

Colorado;Montana↗

Optically stimulated luminescence dating of aeolian sand in the otindag dune field and holocene climate change

The dune system in Otindag sand field of northern China is sensitive to climate change, where effective moisture and related vegetation cover play a controlling role for dune activity and stability. Therefore, aeolian deposits may be an archive of past environmental changes, possibly at the millennial scale, but previous studies on this topic have rarely been reported. In this study, thirty-five optically stimulated luminescence (OSL) ages of ten representative sand-paleosol profiles in Otindag sand field are obtained, and these ages provide a relatively complete and well-dated chronology for wet and dry variations in Holocene. The results indicate that widespread dune mobilization occurred from 9.9 to 8.2 ka, suggesting a dry early Holocene climate. The dunes were mainly stabilized between 8.0 and 2.7 ka, implying a relatively wet climate, although there were short-term penetrations of dune activity during this wet period. After ???2.3 ka, the region became dry again, as inferred from widespread dune activity. The "8.2 ka" cold event and the Little Ice Age climatic deterioration are detected on the basis of the dune records and OSL ages. During the Medieval Warm Period and the Sui-Tang Warm Period (570-770 AD), climate in Otindag sand field was relatively humid and the vegetation was denser, and the sand dunes were stabilized again. These aeolian records may indicate climate changes at millennial time scale during Holocene, and these climatic changes may be the teleconnection to the climate changes elsewhere in the world. ?? Science in China Press and Springer-Verlag GmbH 2008.

Science in China, Series D: Earth Sciences↗

Testing earthquake prediction algorithms: Statistically significant advance prediction of the largest earthquakes in the Circum-Pacific, 1992-1997

Algorithms M8 and MSc (i.e., the Mendocino Scenario) were used in a real-time intermediate-term research prediction of the strongest earthquakes in the Circum-Pacific seismic belt. Predictions are made by M8 first. Then, the areas of alarm are reduced by MSc at the cost that some earthquakes are missed in the second approximation of prediction. In 1992-1997, five earthquakes of magnitude 8 and above occurred in the test area: all of them were predicted by M8 and MSc identified correctly the locations of four of them. The space-time volume of the alarms is 36% and 18%, correspondingly, when estimated with a normalized product measure of empirical distribution of epicenters and uniform time. The statistical significance of the achieved results is beyond 99% both for M8 and MSc. For magnitude 7.5 + , 10 out of 19 earthquakes were predicted by M8 in 40% and five were predicted by M8-MSc in 13% of the total volume considered. This implies a significance level of 81% for M8 and 92% for M8-MSc. The lower significance levels might result from a global change in seismic regime in 1993-1996, when the rate of the largest events has doubled and all of them become exclusively normal or reversed faults. The predictions are fully reproducible; the algorithms M8 and MSc in complete formal definitions were published before we started our experiment [Keilis-Borok, V.I., Kossobokov, V.G., 1990. Premonitory activation of seismic flow: Algorithm M8, Phys. Earth and Planet. Inter. 61, 73-83; Kossobokov, V.G., Keilis-Borok, V.I., Smith, S.W., 1990. Localization of intermediate-term earthquake prediction, J. Geophys. Res., 95, 19763-19772; Healy, J.H., Kossobokov, V.G., Dewey, J.W., 1992. A test to evaluate the earthquake prediction algorithm, M8. U.S. Geol. Surv. OFR 92-401]. M8 is available from the IASPEI Software Library [Healy, J.H., Keilis-Borok, V.I., Lee, W.H.K. (Eds.), 1997. Algorithms for Earthquake Statistics and Prediction, Vol. 6. IASPEI Software Library]. ?? 1999 Elsevier Science B.V. All rights reserved.

Physics of the Earth and Planetary Interiors↗

USGS research on Florida's isolated freshwater wetlands

The U.S. Geological Survey (USGS) has studied wetland hydrology and its effects on wetland health and ecology in Florida since the 1990s. USGS wetland studies in Florida and other parts of the Nation provide resource managers with tools to assess current conditions and regional trends in wetland resources. Wetland hydrologists in the USGS Florida Water Science Center (FLWSC) have completed a number of interdisciplinary studies assessing the hydrology, ecology, and water quality of wetlands. These studies have expanded the understanding of wetland hydrology, ecology, and related processes including: (1) the effects of cyclical changes in rainfall and the influence of evapotranspiration; (2) surface-water flow, infiltration, groundwater movement, and groundwater and surfacewater interactions; (3) the effects of water quality and soil type; (4) the unique biogeochemical components of wetlands required to maintain ecosystem functions; (5) the effects of land use and other human activities; (6) the influences of algae, plants, and invertebrates on environmental processes; and (7) the effects of seasonal variations in animal communities that inhabit or visit Florida wetlands and how wetland function responds to changes in the plant community.

Florida↗

Patterns of marsh surface accretion rates along salinity and hydroperiod gradients between active and inactive coastal deltaic floodplains

High subsidence rates are inherent to coastal deltas worldwide, contributing to rapid rates of relative sea-level rise and compromising the sustainability of coastal wetlands. Different parts of river deltas, however, experience accretion or erosion, depending on the coupling between ecological and morphological processes. Wetland expansion occurs in active deltaic coastal basins that are connected to riverine sedimentation. In contrast, wetland degradation occurs in inactive deltaic coastal basins where river engineering strategies associated with flood control restrict river connectivity. Here, we investigated the relative role of inorganic and organic loading to marsh accretion rates spanning fresh to brackish to saline zones between active and inactive coastal deltaic floodplains of the Mississippi River Delta. Marsh surface accretion rates monitored over 36 months using the feldspar marker horizon technique ranged from 1.24 ± 0.35 cm yr −1 in the freshwater marsh to 2.94 ± 0.51 cm yr −1 in the saline marsh in the inactive coastal basin compared to an opposite trend in the active coastal basin with a low vertical accretion rate in the saline site at 1.12 ± 0.17 cm yr −1 and higher accretion values at the freshwater site (2.14 ± 0.49 cm yr −1 ). Our results suggest that saline marshes have high resilience identified by high vertical accretion rates exceeding those of river-dominated freshwater marshes in active deltaic floodplains. Overall, the marsh surface accretionary patterns detected in this study underscores the relative contribution of organic and inorganic sediments to elevation capital across salinity gradients between active and inactive basins in coastal Louisiana with particular interest to river management and restoration strategies. These findings, however, are applicable to coastal deltaic floodplains elsewhere given the repetition geomorphic forcings (e.g., relative contribution of riverine, tidal and wave power) and coastal typologies worldwide.

Estuarine, Coastal, and Shelf Science↗

Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation

Observations of enhanced volcanic frequency during the last deglaciation have led to the hypothesis that ice unloading in glaciated volcanic terrains can promote volcanism through decompression melting in the shallow mantle or a reduction in crustal magma storage time. However, a direct link between regional climate change, isostatic adjustment, and the initiation of volcanism remains to be demonstrated due to the difficulty of obtaining high-resolution well-dated records that capture short-term climate and volcanic variability traced to a particular source region. Here we present an exceptionally resolved record of 19 tephra layers paired with foraminiferal oxygen isotopes and alkenone paleotemperatures from marine sediment cores along the Southeast Alaska margin spanning the last deglacial transition. Major element compositions of the tephras indicate a predominant source from the nearby Mt. Edgecumbe Volcanic Field (MEVF). We constrain the timing of this regional eruptive sequence to 14.6–13.1 ka. The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ 18 O sw ) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.

Earth and Planetary Science Letters↗

Inhalable desert dust, urban emissions, and potentially biotoxic metals in urban Saharan-Sahelian air

Saharan dust incursions and particulates emitted from human activities degrade air quality throughout West Africa, especially in the rapidly expanding urban centers in the region. Particulate matter (PM) that can be inhaled is strongly associated with increased incidence of and mortality from cardiovascular and respiratory diseases and cancer. Air samples collected in the capital of a Saharan–Sahelian country (Bamako, Mali) between September 2012 and July 2013 were found to contain inhalable PM concentrations that exceeded World Health Organization (WHO) and US Environmental Protection Agency (USEPA) PM 2.5 and PM 10 24-h limits 58 – 98% of days and European Union (EU) PM 10 24-h limit 98% of days. Mean concentrations were 1.2-to-4.5 fold greater than existing limits. Inhalable PM was enriched in transition metals, known to produce reactive oxygen species and initiate the inflammatory response, and other potentially bioactive and biotoxic metals/metalloids. Eroded mineral dust composed the bulk of inhalable PM, whereas most enriched metals/metalloids were likely emitted from oil combustion, biomass burning, refuse incineration, vehicle traffic, and mining activities. Human exposure to inhalable PM and associated metals/metalloids over 24-h was estimated. The findings indicate that inhalable PM in the Sahara–Sahel region may present a threat to human health, especially in urban areas with greater inhalable PM and transition metal exposure.

Bamako↗

Book review: The future of Antarctica

A conference on Antarctica: an Exploitable Resource too Valuable to Develop? took place at the Sir Robert Menzies Centre for Australian studies at the University of London in either late 1989 or early 1990. The papers were compiled into this small book (only 104 pages of text exclusive of useful appendices containing maps, texts of the Antarctic treaty and the Convention on the regulation of Antarctic Mineral Resource Activity [CRAMRA]) which addresses the hottest issues confronting the Antarctic Treaty Consultative Parties in the early 1990’s. Some of the discussion is being overtaken by events, but fortunately, the general quality and broadness of the coverage will make the book useful to diplomats, historians, international lawyers, scientists and other environmentalists for some time to come.

Antarctic Science↗

Biogeochemical redox processes and their impact on contaminant dynamics

Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

Environmental Science & Technology↗

Response of Pacific walruses to disturbances from capture and handling activities at a haul-out in Bristol Bay, Alaska

Observations were made on hems of the Pacific walrus (Odobenus rosmarus divergens) to study their response during the capturing and handling of adult males in summer 1995 at a haul-out at Cape Peirce in southwestern Alaska. Three behaviors (alertness, displacement, and dispersal) were quantified from 16 capture sessions. Herd sizes ranged from 622 to 5,289 walruses. Handling of an immobilized walrus consisted of attempts to attach telemetry devices to the tusks and collect various biological samples. Handling activities resulted in an average of about 10-fold or greater levels of behavior in alertness, displacement, and dispersal than during precapture and darting periods. High levels of behavior usually occurred within the first 45 min of handling. In 8 of 10 capture sessions, walruses returned to predisturbance levels of behavior within 40 min of cessation of the handling disturbance. Alertness and displacement were moderately and negatively correlated with herd size during the handling period, which may reflect an effect of a threshold distance from the point of disturbance to responding individuals. Observations of walruses tagged with VHF radio transmitters indicated that the activities from a given capture session did not preclude tagged walruses from using the haul-out over a subsequent 11-wk monitoring period. Moreover, non-tagged walruses continued to extensively use the haul-out during and after the period in which capture sessions were conducted.

Marine Mammal Science↗

Paenibacillus thiaminolyticus is not the cause of thiamine deficiency impeding lake trout ( Salvelinus namaycush ) recruitment in the Great Lakes

Thiamine (vitamin B 1 ) deficiency is a global concern affecting wildlife, livestock, and humans. In Great Lakes salmonines, thiamine deficiency causes embryo mortality and is an impediment to restoration of native lake trout ( Salvelinus namaycush ) stocks. Thiamine deficiency in fish may result from a diet of prey with high levels of thiaminase I. The discoveries that the bacterial species Paenibacillus thiaminolyticus produces thiaminase I, is found in viscera of thiaminase-containing prey fish, and causes mortality when fed to lake trout in the laboratory provided circumstantial evidence implicating P. thiaminolyticus . This study quantified the contribution of P. thiaminolyticus to the total thiaminase I activity in multiple trophic levels of Great Lakes food webs. Unexpectedly, no relationship between thiaminase activity and either the amount of P. thiaminolyticus thiaminase I protein or the abundance of P. thiaminolyticus cells was found. These results demonstrate that P. thiaminolyticus is not the primary source of thiaminase activity affecting Great Lakes salmonines and calls into question the long-standing assumption that P. thiaminolyticus is the source of thiaminase in other wild and domestic animals.

Great Lakes↗

Digitized analog boomer seismic-reflection data collected during U.S. Geological Survey cruises Erda 90-1_HC, Erda 90-1_PBP, and Erda 91-3 in Mississippi Sound, June 1990 and September 1991

The U.S. Geological Survey (USGS) Coastal and Marine Geology Program has actively collected geophysical and sedimentological data in the northern Gulf of Mexico for several decades, including shallow subsurface data in the form of high-resolution seismic-reflection profiles (HRSP). Prior to the mid-1990s most HRSP data were collected in analog format as paper rolls of continuous profiles up to 25 meters long. A large portion of this data resides in a single repository with minimal metadata. As part of the National Geological and Geophysical Data Preservation Program, scientists at the USGS St. Petersburg Coastal and Marine Science Center are converting the analog paper records to digital format using a large-format continuous scanner. This report, along with the accompanying USGS data release (Bosse and others, 2017), serves as an archive of seismic profiles with headers, converted Society of Exploration Geophysicists Y format (SEG-Y) files, navigation data, and geographic information system data files for digitized boomer seismic-reflection data collected from the Research Vessel (R/V) Erda during two cruises in 1990 and 1991. The Erda 90-1 geophysical cruise was conducted in two legs. The first leg included seismic data collected from the Hancock County region of the Mississippi Sound (Erda 90-1_HC) from June 4 to June 6, 1990. The second leg included seismic data collected from the Petit Bois Pass area of Mississippi Sound (Erda 90-1_PBP) from June 8 to June 9, 1990. The Erda 91-3 cruise occurred between September 12 and September 23, 1991, and surveyed the Mississippi Sound region just west of Horn Island, Mississippi.

Data Series↗

Results of the Analyses for 1,4-Dioxane of Groundwater Samples Collected in the Tucson Airport Remediation Project Area, South-Central Arizona, 2006-2009

Extensive groundwater contamination resulting from industrial activities led to the listing of the Tucson International Airport Area (TIAA) as a Superfund Site by the U.S. Environmental Protection Agency (USEPA) in 1983. Early investigations revealed elevated levels of volatile organic compounds (VOCs), including the chlorinated solvents trichloroethylene and perchloroethylene, in wells in the area. Several responsible parties were identified, and cleanup activities were initiated in the late 1980s using technology designed for removal of VOCs. In 2002, the compound 1,4-dioxane was discovered in wells in the TIAA area. Since then, 1,4-dioxane has been detected throughout the TIAA area at levels exceeding the USEPA Drinking Water Health Advisory value of 3 micrograms per liter (ug/L; U.S. Environmental Protection Agency, 2006). Chemical properties of 1,4-dioxane make it relatively unaffected by the treatment technologies employed in the TIAA area. In 2006, the U.S. Geological Survey (USGS) Arizona Water Science Center, in cooperation with the U.S. Air Force Center for Engineering and the Environment, began an investigation into the extent of groundwater contamination by 1,4-dioxane in the area. Five rounds of groundwater sampling in the TIAA area have been completed by the USGS since that time, yielding a total of 210 samples. Results from these analyses indicate less than reportable concentrations of 1,4-dioxane in 30 percent of the samples, with 46 percent of the samples having concentrations at or above the USEPA Drinking Water Health Advisory level.

Open-File Report↗

A survey of Bureau of Land Management employees on collaboration and alternative dispute resolution

The Bureau of Land Management (BLM) has been actively expanding its capacity to work cooperatively with other agencies, Tribes, the public, and other stakeholders using collaborative and alternative dispute resolution (ADR) approaches. In 1997, the BLM created the BLM’s Collaboration and Alternative Dispute Resolution Program (Collaboration/ADR Program) to centralize, strengthen, and coordinate these efforts. Specifically, the Collaboration/ADR Program is charged with developing ADR policies; ensuring that statutory and regulatory requirements are met; and providing training, resources, and direct support for collaboration and ADR in the BLM. At the request of the Collaboration/ADR Program, the Policy Analysis and Science Assistance Branch of the U.S. Geological Survey, located in the Fort Collins Science Center, conducted an online survey of BLM employees in early 2013 to address four overarching questions: What information sources and assistance resources are BLM employees currently accessing to fill their conflict/dispute resolution and collaboration needs? What are the perceived information and resource needs of BLM employees associated with conflict/dispute resolution and collaboration? What information and resources can the BLM Collaboration/ADR Program provide to fill BLM employee needs? What is the BLM employee level of knowledge associated with conflict/dispute resolution and collaboration? What are the attitudes and perceptions of BLM employees toward conflict/dispute resolution and collaboration? This report describes the findings of this online survey and will assist the BLM’s Collaboration and ADR Oversight Committee in developing the Strategic Plan for the Collaboration/ADR Program. The purpose of the Strategic Plan is to advance collaboration in the BLM and to increase the capacity of the Collaboration/ADR Program to support collaborative efforts on the ground. In March 2013, a user-specific link to the online survey was sent via email to all current BLM employees ( n = 6,734) that could potentially have had experience in collaboration and conflict resolution based on their job series. The links took the respondents to a webpage where the survey was administered. Email reminders were sent at weekly intervals thereafter. When the survey closed in May 2013, the response rate was 45 percent (3,161 employees). Of these, only 14 percent (427 respondents) indicated that they did not have direct experience with collaboration or ADR, and were unlikely to gain experience in the future. Because these respondents were not the target population of this survey, they were branched to the demographic questions at the end of the survey and were not included in any further analyses. The remaining 86 percent (2,734 respondents) indicated that either they did have direct experience with collaboration and (or) ADR, or that they might gain experience with one or both in the future. Below we highlight some of the key findings from their survey responses (refer to the Results section for a comprehensive report of the survey findings).

Open-File Report↗

Flood-inundation maps for the Pawtuxet River in West Warwick, Warwick, and Cranston, Rhode Island

A series of 15 digital flood-inundation maps was developed for a 10.2-mile reach of the Pawtuxet River in the municipalities of West Warwick, Warwick, and Cranston, Rhode Island, by the U.S. Geological Survey (USGS), in cooperation with the Rhode Island Emergency Management Agency and the U.S. Army Corps of Engineers. The coverage of the maps extends downstream from Natick Pond dam near State Route 33/Providence Street bridge in West Warwick to the mouth of the river at Pawtuxet Cove (Broad Street bridge) on the border between Cranston and Warwick, R.I. A one-dimensional step-backwater hydraulic model created and calibrated for the Federal Emergency Management Agency Flood Insurance Studies for Kent and Providence Counties in 2015 was updated for this study. The updated hydraulic model reflects the removal of the Pawtuxet Falls dam during 2011 and the raised elevation of a levee surrounding the Warwick Sewer Authority wastewater treatment facility during 2014–17. The hydraulic model was calibrated by using the current (2018) stage-discharge relation at the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) and documented high-water marks from the March 31, 2010, flood, which had a peak flow greater than the estimated 0.2-percent annual exceedance probability floodflow. The hydraulic model was used to compute water-surface profiles for 15 flood stages at 1-foot (ft) intervals referenced to the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) and ranging from 8.0 ft (15.2 ft, North American Vertical Datum of 1988), which is the National Weather Service Advanced Hydrologic Prediction Service flood category “action stage,” to 22.0 ft (29.2 ft, North American Vertical Datum of 1988), which is the maximum stage of the stage-discharge relation at the streamgage and exceeds the National Weather Service Advanced Hydrologic Prediction Service flood category “major flood stage” of 13.0 ft. The simulated water-surface profiles were combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data with a 1.0-ft vertical accuracy to create flood-inundation maps. The flood-inundation maps depict estimates of the areal extent and depth of flooding corresponding to 15 selected flood stages at the streamgage. The flood-inundation maps depict only riverine flooding and do not depict any tidal backwater or coastal storm surge that might occur in the lower part of the river reach. The flood-inundation maps can be accessed through the USGS Flood Inundation Mapping Science website at https://water.usgs.gov/osw/flood_inundation . Near-real-time stages and discharges at the Pawtuxet River streamgage can be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/ . The National Weather Service Advanced Hydrologic Prediction Service provides flood forecasts of stage for this site (CRAR1) at https:/water.weather.gov/ahps/ . The availability of flood-inundation maps referenced to current and forecasted water levels at the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) can provide emergency management personnel and residents with information that is critical for flood response activities, such as evacuations and road closures, and postflood recovery efforts. The flood-inundation maps are nonregulatory but provide Federal, State, and local agencies and the public with estimates of the potential extent of flooding during flood events.

Rhode Island↗